He was assigned to an observation squadron based near Tellancourt that flew Aviatiks. They were quartered in a beautiful and disintegrating château abandoned by its owners. It was the dead of winter. He was given one of the smallest rooms in the back, with a faulty stove. He flew across the lines every day the weather allowed, then moved on to artillery spotting.

After cocoa and biscuits at 4:30 a.m., he climbed into his flying suit with Hans a part of his thoughts each bitterly cold morning. Once he and his observer finished dressing, they were bundled like bears in fur, their faces below their goggles greased for protection against the wind. The airfield was a cinder runway cut through acres of beet and kale.

When the engine turned over, warm oil misted back and they were constantly wiping their goggles. With any sideslips, great blasts of air buffeted around the windscreen. At altitude they occasionally found themselves in the trajectories of the big shells. The plane rocked like a canoe whenever one went by. Their anti-aircraft fire used black cordite, which lingered after the fighting had passed over. Traversing a belt of it during a calm stretch produced an uneasiness he couldn’t locate until later, when he smelled his flying clothes.

At six thousand meters, the entire western front from the Alps to the North Sea was visible. They had the sky to themselves.

Where were the French planes? They didn’t know. They studied the great Boelcke’s discourse on the techniques of air fighting. After his death, the order had been given that every airman should be able to repeat it verbatim. At the funeral it was said that Richthofen himself had pledged, “I will be a Boelcke.”

They were not Boelckes. They knew only a few things.

Murnau’s first enemy plane was a light blue Caudron, lumbering along against the wind. He and his observer came across it when straggling back alone after a cannister-drop. It looked like a flying wire entanglement. They approached to within a hundred yards and did nothing, staring at the two miniature humans in their French birdcage. Why kill them? Why even shoot at them?

The French observer suffered no such inhibitions, and splintered Murnau’s observer’s goggles. After they landed, the observer was carried off to a field hospital and never seen again.